Mooring devices

ABSTRACT

A mooring device is disclosed with a float to be held at a given depth and including a sinker, means linking the float and the sinker together, a cable connecting the float to the sinker and means mounted on the sinker for paying out the cable, means for disabling the paying out means on the impact of the sinker with the sea bed, and means associated with the linking means for releasing the linking means at a preset depth.

United States Patent Leslie Gerald Bullen Dartmouth, Nova Scotia, Canada 842,286

July 16, 1969 Jan. 4, 1972 EMI Limited Hayes, England July 16, 1968 Great Britain lnventor Appl. No. Filed Patented Assignee Priority MOORING DEVICES 5 Claims, 8 Drawing Figs.

US. Cl... 9/8 Int. Cl 1363b 21/52 Field of Search 9/8, 9;

[56] References Cited UNITED STATES PATENTS 3,039,419 6/1962 Rimar 1 14/209 3,319,595 5/1967 Van Dorn et al. 9/8 X 3,336,892 8/1967 Barry et al. 9/8X 3,471,877 10/ 1 969 Bayles 9/8 3,500,209 3/1970 Fletcher et a1. 9/8 X 3,372,665 3/ 1968 Mesler 9/8 X Primary Examiner-Milton Buchler Assistant Examiner-Gregory W. OConnor Att0rney-William W. Downing, Jr.

ABSTRACT: A mooring device is disclosed with a float to be held at a given depth and including a sinker, means linking the float and the sinker together, a cable connecting the float to the sinker and means mounted on the sinker for paying out the cable, means for disabling the paying out means on the impact of the sinker with the sea bed, and means associated with the linking means for releasing the linking means at a preset depth.

PATENTEB JAN 41972 Fig.2o

SHEET 2 OF 3 MOORING DEVICES This invention relates to mooring devices, and in particular to mooring devices which include a float intended for mooring for example, a buoy from below the surface of the sea.

For oceanographic navigational and other purposes it is sometimes desired to provide a submarine-mooring point at a given depth below the surface of the sea, and various proposals have been made for achieving this result. For example, a float may be attached to a sinker or anchor by a predetermined length of cable so that where the depth of the sea is known the float is moored at a given depth; however, in deep water sounding cannot'be obtained with sufficient accuracy to ensure that the float is moored at the right depth. To overcome this difficulty various relatively complicated depthsensitive devices have been used to control a cable winch on the float so that the float is allowed to rise by paying out the cable until the float is at the desired depth and is then maintained there by braking the winch, but such complicated arrangements require skilled adjustments and the sensitive moving parts are easily damaged and are quickly affected by corrosion.

It is an object of the present invention to provide a mooring device for mooring a float at a particular depth which device is relatively simple but none the less accurate.

According to the present invention from one aspect there is provided a mooring device including a float to be held at a given depth, a sinker, a manacle linking said float and said sinker by means of a locking rod, a cable connecting said float to said sinker, means sensitive to fluid pressure for withdrawing said locking rod at a present depth so as to release said manacle, means carried by said sinker for paying out said cable, and means for preventing further payout of said cable on the impact of said sinker with the sea bed.

According to the present invention from another aspect there is provided a mooring device including a float to be held at a given depth, a sinker, means linking said float and said sinker together, a cable connecting said float to said sinker, means associated with said linking means for releasing said linking means at a preset depth, means carried by said sinker for paying out said cable, and an inertial lock carried by said sinker for preventing further payout of said cable on the impact of said sinker with the sea bed.

In order that the invention may be fully understood and readily carried into effect, it will now be described with reference to the accompanying drawings, in which:

FIG. 1 is a diagram partly in section showing a mooring device according to one example of the invention before launching,

FIGS. 2a, 2b, 2c, 2d, 2e and 2f which show various stages in the operation of the mooring device FIG. 3 is a diagram partly in section showing part of FIG. 1 in detail.

In the following device according to the invention a dead weight sinker or anchor carrying a mooring cable and attached to form a unit with a float or buoyant chamber is launched into the sea and descends taking the float with it, the unit as a whole having negative buoyancy. At a predetermined depth the sinker is freed from the float and descends rapidly paying out mooring cable from a drum within its casings. As the sinker descends the float rises but at a much slower speed, its rate of ascent being reduced for example by means of a drogue. The predetermined depth (or separation depth) is chosen so that during the time taken for the sinker to reach the sea bed the float has risen to its required implantation depth, the sinker including means which on its impact with the sea bed the mooring cable payout system is locked so that the float is held at the required depth.

The mooring device shown in FIG. 1 has three major components, a sinker or dead weight anchor l, a float or buoyant chamber 2 and a surface buoy 3. The sinker 1 includes a winch on which is wound the lower mooring cable for the float 2 and means for preventing payout of the cable on impact of the sinker with the sea bed; neither the winch nor the locking means is shown in FIG. 1 but will be described subsequently.

The sinker l is linked to the float 2 by means of a manacle 4 which includes a release mechanism operated by an adjustable depth-sensitive release means. Screwjacks 6 are provided to ensure the rigidity of the attachment of the sinker l to the float 2. The float 2 also has linked to it the surface buoy 3 by a split cylindrical casing 9 having suitable attachment means and secured by two bands with a timed release arrangement and in addition, an upper cable 8 is provided joining the buoy 3 to the float 2, the cable being coiled round a stabilizing weight 7 and its telescopic mounting 13. The coil of cable 8 may conveniently be kept in shape by embedding it in a nonadhesive potting compound. The buoy 3 carries a transponder assembly 10 with aerials 11 and a lamp 12. To facilitate handling of the device before launching a sling I4 is provided attached to the float 2.

The operation of the mooring device shown in FIG. I will now be described with reference to FIGS. 2a to 2fwhich show various stages. In FIG. 2a the device is launched by lowering it into the sea by means of a cable attached to the sling 14. The device is arranged to have overall negative buoyancy so that on release of the cable it falls throughlthe sea until a predetermined depth is reached when the manacle 4 is released by the depth sensitive means allowing the sinker l to fall and the float 2 to rise as shown in FIG. 2b.

Referring to FIG. 3, the manacle 4 is split at one end, having projections designated by reference "33, one projection for each half of the manacle. The other end is also split but has a spring-loaded hinge 32 keeping it together. The manacle 4 is kept in a clamping position over rings respectively on the underside of the float 2 and the top side of the sinker 1, thus connecting sinker and float, by means of a locking rod 19 through the projections 33. Rod 19 bears against a movable plate 30 associated with an 0" ring 31 inside a cylinder 5. A spring 27 is loaded against plate 30 by means of an adjusting screw 28 bearing against a further plate 29. At a given depth the sea pressure overcomes the load in the spring 27 allowing rod 19 to withdraw from its locking position, the manacle 4 to open, and sinker I and float 2 to part. The depth at which this occurs can be preset by adjusting the load in the spring 27 by means of adjusting screw 28. Alternatively the release means can comprise a timed corrosion link timed to release the sinker and float at a preset depth. Referring back to FIG. 2b as soon as the sinker 1 leaves the float 2 the screwjacks 6 and sling 14 also fall away. The sinker 1 now descends rapidly towards the sea bed paying out cable 15 from a winch inside itself as it goes. At the same time the float 2 carrying the buoy 3 rises to the surface under the influence of its buoyancy, but its rate of ascent is slowed by a drogue 16 attached to the bottom of the float 2 and brought into action when the sinker 1 falls away; this is shown in FIG. 20. In FIG. 2d the sinker 1 has struck the sea bed and further payout of the cable 15 is prevented, and by this time the float 2 and buoy 3 will have risen to the required implantation depth for the float 2, the drogue 16 now being allowed to fall away by a suitable timing mechanism, such as for example a timed corrosion link. As shown in FIG. 2e time from launching the casing 9 is released, by a further timed corrosion link for example, allowing the buoy 3 to rise to the surface as shown in FIG. 2f it being secured to the float 2 by the upper cable 8. The cable 8 may include floats 17 and weights 18 to 'ensure that under the worst conditions the cable 8 does not approach the surface nor sink below the float 2 and become entangled with it.

In the example of the device according to the invention shown in FIG. I the sinker 1 has the form of a hollow steel ellipsoid of revolution which together with the winch inside it has a weight in water of about 600 lbs. The sinker is provided with three small slots spaced around the casing to provide fixing points for the three jacks 6. The cable 15, that is to say, the lower mooring cable is wound on the winch within the sinker l and consists of 8,000 ft. of 4a-inch diameter steel cable. In the present example the winch in the sinker 1 takes the form of a nonrotatable spool with its axis along the long axis of the ellipsoid on which the cable is wound, with a rotatable fair-lead feeding the cable through the top of the sinker when the sinker strikes the sea bed an inertial lock prevents further rotation of the fair-lead and therefore restricts further paying out of the cable. This is shown in detail in FlG. 3, which shows the spool made up of a central spindle 26 on which is wound the cable leading through a rotating fair-lead 20. The inertial lock comprises two massive weights 23 mounted on springs 24 and holding respective locking plungers 21 against springs 22. When the sinker 1 hits the sea bed, the inertia of weights 23 causes them to continue in motion against springs 24 allowing locking plungers 21 to spring out and clamp the rotating fairlead 20, preventing its rotation and subsequent payout of cable 15. Alternatively the locking means could be arranged to work on the winch itself or the cable itself to prevent further payout; or the winch would be rotatable.

The float 2 is cylindrical with bowed ends and includes mountings for the jacks 6 in addition to the attachments for the sling 14. The drogue 16 takes the form ofa hemispherical shell approximately 4 feet in diameter and is attached to the lower mooring cable 15 at a point near its upper end. During the phase of the operation of the device shown in FIG. the drogue is also attached at its lower end to the cable 15; after 6 to 12 hours the attachment of the drogue to the float 2 and to the cable 15 is arranged to release and allow the drogue to sink in the sea. Instead of a drogue rigid flaps attached to the float 2 can be used.

The upper cable 8 is of 7/16 inch diameter braided polypropylene and in the sea is approximately neutrally buoyant. The surface buoy 3 is of glass fiber reinforced synthetic resin formed into a hollow sphere with attachments at the upper and lower end for the transponder 10 and the balance weight 13.

The rate of descent of the sinker l is arranged to be say, fifteen times the rate of ascent of the float 2 and buoy 3 so that errors of say l50 feet in the estimated depth of the sea at the point ofimplantation of the buoy will lead to an error of only l0 feet in the implantation depth of the float 2. Other errors in the implantation depth of the float 2 can arise from inaccuracy in the depth-sensitive release means for the manacle 4 and from variations in the rates of descent of the sinker l and ascent of the float 2 and buoy 3, but it is believed that the implantation depth of the float 2 can be achieved to a total tolerance of feet.

Clearly the implantation depth ofthe float 2 can be adjusted by adjusting the separation depth at which the manacle 4 is released by the depth sensitive release means.

It will be appreciated that as all of the packaging components such as the manacle 4, thejacks 6 and the casing 9, and in addition the drogue l6 are allowed to fall away from the mooring device by means of timed corrosion links during successive stages of its implantation, the float 2 after implantation will present little drag to sea currents and therefore the system will be less affected by variations in the sea currents. As the device has overall negative buoyancy in extreme conditions the buoy 3 will be dragged under the surface of the sea rather than the anchor I being lifted clear ofthe sea bed.

lclaim:

l. A mooring device including a float to be held at a given depth, a sinker, a manacle linking said float and said sinker by means of a locking rod, a cable connecting said float to said sinker, means sensitive to fluid pressure for withdrawing said locking rod at a present depth so as to release said manacle, means carried by said sinker for paying out said cable, and means for preventing further payout of said cable on the impact of said sinker with the sea bed.

2. A mooring device including a float to be held at a given depth, a sinker, a manacle linking said float and said sinker by means of a locking rod, a cable connecting said float to said sinker, means sensitive to fluid pressure for withdrawing said locking rod at a preset depth, means carried by said sinker for paying out said cable, and an inertial look carried by said sinker for preventing further payout of said cable on the impact ofsaid sinker with the sea bed.

3. A device according to claim 2, including means for slowing the ascent of said float when released from said sinker, so as to constrain said float to reach a given depth by the time said sinker reaches the sea bed.

4. A device according to claim 3, in which said means for slowing the ascent comprises a drogue.

5. A device according to claim 2, in which said paying out means comprises a winch on which said cable is wound as a nonrotatable spool, and a rotatable fair-lead, said inertial look being adapted to lock said fair-lead on the impact of said sinker with the sea bed. 

1. A mooring device including a float to be held at a given depth, a sinker, a manacle linking said float and said sinker by means of a locking rod, a cable connecting said float to said sinker, means sensitive to fluid pressure for withdrawing said locking rod at a present depth so as to release said manacle, means carried by said sinker for paying out said cable, and means for preventing further payout of said cable on the impact of said sinker with the sea bed.
 2. A mooring device including a float to be held at a given depth, a sinker, a manacle linking said float and said sinker by means of a locking rod, a cable connecting said float to said sinker, means sensitive to fluid pressure for withdrawing said locking rod at a preset depth, means carried by said sinker for paying out said cable, and an inertial look carried by said sinker for preventing further payout of said cable on the impact of said sinker with the sea bed.
 3. A device according to claim 2, including means for slowing the ascent of said float when released from said sinker, so as to constrain said float to reach a given depth by the time said sinker reaches the sea bed.
 4. A device according to claim 3, in which said means for slowing the ascent comprises a drogue.
 5. A device according to claim 2, in which said paying out means comprises a winch on which said cable is wound as a nonrotatable spool, and a rotatable fair-lead, said inertial look being adapted to lock said fair-lead on the impact of said sinker with the sea bed. 